1. Field of the Invention
The present invention relates to a scan method for driving a display and a display therewith, and more particularly, to a multiple scan method for driving a display and a display therewith, by dividing active pixel area and alternately driving these divided active pixel area for expediting response time of these active pixels in the display.
2. Description of Related Art
As computer technology advances and as Internet and multimedia are highly being developed, current information is transmitted in digital form instead of analog form, and novel display apparatuses are being invented. A conventional CRT, structured with an inner electronic cavity structure occupying substantial space, and radiation harmful to human eyes, is gradually being eliminated from the display market. Therefore, a flat panel display fabricated with optoelectronic technology and semiconductor process, such as a liquid crystal display (LCD), an organic light emitting display (OLED), or a plasma display panel (PDP) display, is becoming main trend of research and development.
A plurality of pixels arranged in an array constitutes a frame in a display. The pixel is a basic unit for displaying in the display. In a flat panel display, for example, a driving potential is generated according to a pixel data to charge the pixel for showing luminance accordingly. A display is generally driven by a horizontal sync signal and a vertical sync signal, which is applied to a gate driving unit and a source driving unit respectively. The horizontal sync signal determines a number of rows to display in a specific time period, and the vertical sync signal determines a display time length of each frame. A time interval taken between every two adjacent vertical sync signals is a frame period. The vertical sync signal can as well be characterized with a reciprocal of the frame period, i.e. a frame rate. In general, a frame rate of a computer monitor is not less than 60 Hz, i.e., a display device is able to show more than 60 frame data in a second, where each frame period is no longer than 16.7 ms.
According to the flat panel display technology, an ordinary vertical scanning frequency is 60 Hz. A conventional scanning method is implemented by a source driving unit and a gate driving unit which are operated once of each in a frame period, which is shown in FIG. 1. A display 100 includes a display panel 110, a source driving device 120 and a gate driving device 130. The source driving device 120 includes a plurality of source drivers 121 and the gate driving device 330 includes three gate drivers 102, 104 and 106. Each pixel of the panel in the display is changed one time during the frame period. A charging curve is depicted as an original temporal response curve 410 shown in FIG. 4. The response time of the pixels corresponding to the pixel data is an important issue for improving the display quality for the flat panel display, especially for displaying objects in motion. It is not considered and also difficult in the conventional architecture for improving the response time of the pixels.
Architecture for speeding up the response time of the pixels is proposed in the US Patent Application Publication No. US2002/017640, titled “Method of Display by Sub-Frame Driving”, pub. Date on Nov. 21, 2002. In the architecture, under the same vertical display condition, e.g. a 60 Hz frame rate is provided, that is, a frame lasts for about 16.7 ms. A frame period, where a picture having m×n pixels thereof, is divided into k sub frame periods. A driving potential is applied to the pixels, such that the liquid crystal response time is expedited. The driving potential is a target potential plus a driving offset for respective sub frame period. Referring to FIG. 2, a driving potential waveform diagram of a frame is illustrated, where the frame includes m×n pixels divided into sub-frame-periods of k=2, for example.
In FIG. 2, a first sub frame is displayed between time point ts0 and time point ts1 and a second sub frame is displayed between time point ts1 and time point tsf. A driving potential VO corresponding to the first sub frame is the original target driving potential VD plus a driving offset potential ΔV1. Whereas a driving potential corresponding to the second sub frame is the original target driving potential VD plus a driving offset potential ΔV2, e.g. ΔV2=0. By such driving design, therefore, a response time of a liquid crystal of the LCD is shortened.
According to the conventional art described above, however, the driving offset potential provided is not precise as desired, the driving potential for each sub frame cannot be expected, which results in unstable picture quality in a LCD. Furthermore, the driving offset amount generated according to conventional art is based on an over-driving technique. Therefore, a frame buffer, e.g. an SDRAM in general, for storing pixel data, and a memory, e.g. an electrically erasable programmable read-only memory (EEPROM) in general, for storing a look up table are additionally disposed, for calculating driving offset potential correspondingly.
According to the above descriptions, hardware such as a frame buffer and a memory for storing a look up table are additionally disposed for obtaining driving offset potentials, where a precise driving offset potential is hardly achieved by over-driving technique without complicated calculation mechanism. Therefore, a novel multiple driving method for a LCD is desired, where additional hardware is not needed, and driving potential can be easily and precisely generated.